Boiler Function; Fault Finding - Worcester Gas boiler Installation Instructions Manual

BOILER FUNCTION

7 BOILER FUNCTION
7.1

FAULT FINDING

If in the unlikely event the boiler does not give complete
satisfaction, before calling for a service engineer, the
installer should check the following:-
FOR BOILERS WITH INTEGRAL DIVERTER VALVE AND
CONTROLS
NO CENTRAL HEATING, BUT HOT WATER OK
Remove the room stat wiring from Ls, LR and N from
terminal block ST10. Fit a link between Ls and LR, if the
CH now works there is likely to be a problem with the
room stat or wiring to it.
NO HOT WATER, BUT CENTRAL HEATING OK
If a cylinder stat is used, remove the cylinder stat wiring
from 7 and 9 on the terminal block ST8. Fit link across 7
and 9.
If the HW now functions, there is likely to be a problem
with the cylinder stat or wiring to the stat.
FOR ALL BOILERS WITH INTERNAL OR EXTERNAL
CONTROLS
Burner lights then goes out in DHW or CH mode
Does the boiler run normally with the front cover off and
then fail when the cover is put back on?
If yes there is likely to be a flue problem - either the air
inlet is blocked or the inner flue is leaking flue gases into
the air inlet.
BOILER NOISY OR GOING TO OVERHEAT
1. Was the system flushed?
2. Has the pump been bled and the dust cap released.
GENERAL CHECKS
1. Is all the air bled from the gas supply?
2. Is all the air bled from the primary water system?
3. Is there 230v ac across the boiler live and neutral
terminals?
(L & N on ST10)
4. Is the polarity correct?
5. Is the incoming gas pressure at least 18mbar with the
boiler at maximum output?
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6 720 645 222a (2012/05)